Hilbert's projective metric in quantum information theory

We introduce and apply Hilbert's projective metric in the context of quantum information theory. The metric is induced by convex cones such as the sets of positive, separable or PPT operators. It provides bounds on measures for statistical distinguishability of quantum states and on the decrease of entanglement under LOCC protocols or other cone-preserving operations. The results are formulated in terms of general cones and base norms and lead to contractivity bounds for quantum channels, for instance improving Ruskai's trace-norm contraction inequality. A new duality between distinguishability measures and base norms is provided. For two given pairs of quantum states we show that the contraction of Hilbert's projective metric is necessary and sufficient for the existence of a probabilistic quantum operation that maps one pair onto the other. Inequalities between Hilbert's projective metric and the Chernoff bound, the fidelity and various norms are proven.Comment: 32 pages including 3 appendices and 3 figures; v2: minor changes, published versio

Quantifying Motor Experience in the Infant Brain: EEG Power, Coherence, and Mu Desynchronization

The emergence of new motor skills, such as reaching and walking, dramatically changes how infants engage with the world socially and cognitively. Several examples of how motor experience can cascade into cognitive and social development have been documented, yet a significant knowledge gap remains in our understanding of whether these observed behavioral changes are accompanied by underlying neural changes. We propose that electroencephalography (EEG) measures such as power, coherence, and mu desynchronization are optimal tools to quantify motor experience in the infant brain. In this mini-review, we will summarize existing infant research that has separately assessed the relation between motor, cognitive, or social development with coherence, power, or mu desynchronization. We will discuss how the reviewed neural changes seen in seemingly separate developmental domains may be linked based on existing behavioral evidence. We will further propose that power, coherence, and mu desynchronization be used in research exploring the links between motor experience and cognitive and social development

(±)-3-Carb­oxy-2-(imidazol-3-ium-1-yl)­propanoate

The title compound, C7H8N2O4, crystallizes as a zwitterion, with mol­ecules organized into mol­ecular sheets via carbox­yl–carboxyl­ate and N+—H⋯carboxyl­ate contacts. These sheets are constructed from translationally related mol­ecules that further link to neighboring motifs via π-stacking [centroid–centroid distance 3.504 (3) Å] and weak C—H⋯O contacts

A New Biomarker to Examine the Role of Hippocampal Function in the Development of Spatial Reorientation in Children: A Review

Spatial navigation is an adaptive skill that involves determining the route to a particular goal or location, and then traveling that path. A major component of spatial navigation is spatial reorientation, or the ability to reestablish a sense of direction after being disoriented. The hippocampus is known to be critical for navigating, and has more recently been implicated in reorienting in adults, but relatively little is known about the development of the hippocampus in relation to these large-scale spatial abilities in children. It has been established that, compared to school-aged children, preschool children tend to perform poorly on certain spatial reorientation tasks, suggesting that their hippocampi may not be mature enough to process the demands of such a task. Currently, common techniques used to examine underlying brain activity, such as electroencephalography (EEG) and functional magnetic resonance imaging (fMRI), are not suitable for examining hippocampal development in young children. In the present paper, we argue instead for the use of eyeblink conditioning (EBC), a relatively under-utilized, inexpensive, and safe method that is easy to implement in developing populations. In addition, EBC has a well defined neural circuitry, which includes the hippocampus, making it an ideal tool to indirectly measure hippocampal functioning in young children. In this review, we will evaluate the literature on EBC and its relation to hippocampal development, and discuss the possibility of using EBC as an objective measure of associative learning in relation to large-scale spatial skills. We support the use of EBC as a way to indirectly access hippocampal function in typical and atypical populations in order to characterize the neural substrates associated with the development of spatial reorientation abilities in early childhood. As such, EBC is a potential, simple biomarker for success in tasks that require the hippocampus, including spatial reorientation

Monsters, black holes and the statistical mechanics of gravity

We review the construction of monsters in classical general relativity. Monsters have finite ADM mass and surface area, but potentially unbounded entropy. From the curved space perspective they are objects with large proper volume that can be glued on to an asymptotically flat space. At no point is the curvature or energy density required to be large in Planck units, and quantum gravitational effects are, in the conventional effective field theory framework, small everywhere. Since they can have more entropy than a black hole of equal mass, monsters are problematic for certain interpretations of black hole entropy and the AdS/CFT duality. In the second part of the paper we review recent developments in the foundations of statistical mechanics which make use of properties of high-dimensional (Hilbert) spaces. These results primarily depend on kinematics -- essentially, the geometry of Hilbert space -- and are relatively insensitive to dynamics. We discuss how this approach might be adopted as a basis for the statistical mechanics of gravity. Interestingly, monsters and other highly entropic configurations play an important role.Comment: 9 pages, 4 figures, revtex; invited Brief Review to be published in Modern Physics Letters

Nematodos: indicadores del estado y procesos del suelo en un sistema frutícola

Se estudió la condición del suelo utilizando el análisis de la comunidad de nematodos en distintas coberturas vegetales en los espacios interfilares de un cultivo de pera. Se investigó los efectos de las coberturas (alfalfa+pastos AP, festuca F y vegetación espontánea VE) durante la primavera 2012 y 2013. Se evaluó nematofauna, materia orgánica del suelo (MOS) y materia seca de las coberturas. El aporte de materia seca, la MOS, y los índices de enriquecimiento y de nematodos fitófagos fueron mayores en AP que en los tratamientos VE y F. El índice de estructura fue bajo y no fue afectado por el tratamiento. La relación fungívoros/bacteriófagos indicó que la descomposición de la MOS fue principalmente mediada por bacterias en todas las coberturas. La mezcla AP puede proveer un incremento en la capacidad de reciclado de nutrientes del suelo para el crecimiento de la pera al aumentar los nematodos bacteriófagos.The nematode community analysis in different cover crops at inter-row spaces of a pear orchard was employed to study soil condition. The effects of three cover crop treatments (alfalfa+grasses (AP), fescue (F), and spontaneous vegetation (VE)) were investigated during spring 2012 and 2013. Nematofauna, soil organic matter (SOM) and cover crop dry matter were assessed. Plant feeding nematodes were dominant and comprised more than 50% of the total population in each treatment. The addition of dry matter, SOM, as well as the enrichment and the plant-parasitic indexes were higher in AP than either in VE or F. The structure index was low and was not affected by treatments. The fungivores to bacterivores ratio indicated that the SOM decomposition was mainly mediated by bacteria in all cover crops. AP mixture can increase the soil nutrient recycling capacity for pear trees growth because the number of bacterivores increases.Eje A4: Ambiente, Naturaleza y AgroecologíaFacultad de Ciencias Agrarias y Forestale

Nematodos: indicadores del estado y procesos del suelo en un sistema frutícola

Se estudió la condición del suelo utilizando el análisis de la comunidad de nematodos en distintas coberturas vegetales en los espacios interfilares de un cultivo de pera. Se investigó los efectos de las coberturas (alfalfa+pastos AP, festuca F y vegetación espontánea VE) durante la primavera 2012 y 2013. Se evaluó nematofauna, materia orgánica del suelo (MOS) y materia seca de las coberturas. El aporte de materia seca, la MOS, y los índices de enriquecimiento y de nematodos fitófagos fueron mayores en AP que en los tratamientos VE y F. El índice de estructura fue bajo y no fue afectado por el tratamiento. La relación fungívoros/bacteriófagos indicó que la descomposición de la MOS fue principalmente mediada por bacterias en todas las coberturas. La mezcla AP puede proveer un incremento en la capacidad de reciclado de nutrientes del suelo para el crecimiento de la pera al aumentar los nematodos bacteriófagos.The nematode community analysis in different cover crops at inter-row spaces of a pear orchard was employed to study soil condition. The effects of three cover crop treatments (alfalfa+grasses (AP), fescue (F), and spontaneous vegetation (VE)) were investigated during spring 2012 and 2013. Nematofauna, soil organic matter (SOM) and cover crop dry matter were assessed. Plant feeding nematodes were dominant and comprised more than 50% of the total population in each treatment. The addition of dry matter, SOM, as well as the enrichment and the plant-parasitic indexes were higher in AP than either in VE or F. The structure index was low and was not affected by treatments. The fungivores to bacterivores ratio indicated that the SOM decomposition was mainly mediated by bacteria in all cover crops. AP mixture can increase the soil nutrient recycling capacity for pear trees growth because the number of bacterivores increases.Eje A4: Ambiente, Naturaleza y AgroecologíaFacultad de Ciencias Agrarias y Forestale

Nematodos: indicadores del estado y procesos del suelo en un sistema frutícola

Se estudió la condición del suelo utilizando el análisis de la comunidad de nematodos en distintas coberturas vegetales en los espacios interfilares de un cultivo de pera. Se investigó los efectos de las coberturas (alfalfa+pastos AP, festuca F y vegetación espontánea VE) durante la primavera 2012 y 2013. Se evaluó nematofauna, materia orgánica del suelo (MOS) y materia seca de las coberturas. El aporte de materia seca, la MOS, y los índices de enriquecimiento y de nematodos fitófagos fueron mayores en AP que en los tratamientos VE y F. El índice de estructura fue bajo y no fue afectado por el tratamiento. La relación fungívoros/bacteriófagos indicó que la descomposición de la MOS fue principalmente mediada por bacterias en todas las coberturas. La mezcla AP puede proveer un incremento en la capacidad de reciclado de nutrientes del suelo para el crecimiento de la pera al aumentar los nematodos bacteriófagos.The nematode community analysis in different cover crops at inter-row spaces of a pear orchard was employed to study soil condition. The effects of three cover crop treatments (alfalfa+grasses (AP), fescue (F), and spontaneous vegetation (VE)) were investigated during spring 2012 and 2013. Nematofauna, soil organic matter (SOM) and cover crop dry matter were assessed. Plant feeding nematodes were dominant and comprised more than 50% of the total population in each treatment. The addition of dry matter, SOM, as well as the enrichment and the plant-parasitic indexes were higher in AP than either in VE or F. The structure index was low and was not affected by treatments. The fungivores to bacterivores ratio indicated that the SOM decomposition was mainly mediated by bacteria in all cover crops. AP mixture can increase the soil nutrient recycling capacity for pear trees growth because the number of bacterivores increases.Eje A4: Ambiente, Naturaleza y AgroecologíaFacultad de Ciencias Agrarias y Forestale

Unitarity and the Hilbert space of quantum gravity

Under the premises that physics is unitary and black hole evaporation is complete (no remnants, no topology change), there must exist a one-to-one correspondence between states on future null and timelike infinity and on any earlier spacelike Cauchy surface (e.g., slices preceding the formation of the hole). We show that these requirements exclude a large set of semiclassical spacetime configurations from the Hilbert space of quantum gravity. In particular, the highest entropy configurations, which account for almost all of the volume of semiclassical phase space, would not have quantum counterparts, i.e. would not correspond to allowed states in a quantum theory of gravity.Comment: 7 pages, 3 figures, revtex; minor changes in v2 (version published in Class. Quant. Grav.